Abstract: A loading binary metal oxide Mn-Ni/γ-Al₂O₃ catalyst was synthesized with γ-Al₂O₃ as support and with the transition metals Mn, Ni as active ingredients. The catalyst was characterized by XRD, XRF, BET. Then the catalyst was used for the ozonation advanced treatment of pulping effluent. The relationship between wastewater COD_cr and affecting factors was established via the response surface analysis with Box-Behnken mathematical model. The results showed that the Mn and Ni were loaded on the surface and in the internal hole-channel successfully; After the load of these metals, the particle size decreased, and the specific surface area, pore volume and average pore size decreased by 11.96%, 16.48% and 5.28% respectively. The optimal condition for treatment was initial pH 8.7, catalyst dosage 9.2 g/L and ozone concentration 29.6 mg/L. Under this condition, the removal rates of COD_Cr and AOX with Mn-Ni/γ-Al₂O₃(mole ratio of Mn and Ni 6:4) as catalyst were 75.1% and 85.98% after 30 min treatment (40℃). Furthermore, the removal rate for this catalyst still reached 70.6% after being repeatedly used for 6 times. And the ionic releases of Mn and Ni was remained below 1 mg/L during the reaction, indicating of the high stability and good performance of the Mn-Ni/γ-Al₂O₃ catalyst had for repeated use.

Key words: advanced treatment, γ-Al₂O₃, ozone oxidation, pulping effluent, response surface analysis